It is known that substructural surfaces can be sealed in a waterproof manner by application of pre-formed, flexible membranes of waterproofing pressure-sensitive adhesives. The membranes are protected by a release sheet liner made of waxed paper or plastic that can be peeled from the adhesive at the time of application.
The use of split or perforated release sheets is known in the waterproofing industry. In U.S. Pat. No. 4,172,830, for example, waterproofing membranes were disclosed having, release sheets that were perforated, so that strips could be progressively removed from the adhesive layer, and exposed portions of the adhesive could be overlaid onto the back of adjacent, installed membranes.
Another waterproofing membrane having a pre-split or perforated release liner was disclosed in U.S. Pat. No. 5,916,654 of Phillips et al. It was explained that one of the problems with typical one-piece release sheets is that an applicator may have difficulty removing a large liner without tearing the release liner. Tearing of the release liner made it difficult to remove the remaining liner material, and portions of the release liner that remained on the adhesive layer reduced the area of adhesion.
Phillips et al. therefore disclosed the use of a strip of material placed on the adhesive surface below and between each abutting edge of pre-split release liners to allow sections of the release liners to be removed without the (unwaxed) edges of the liners from sticking. If the release liner was perforated instead of pre-split, the strip material was to be located underneath the perforations. Thus, the strip was useful for preventing edge adhesion of release liners, which otherwise would be difficult to remove, and preventing tearing of the liner material which would leave liner material remaining on the adhesive surface. The strip disclosed by Phillips et al. could also served to prevent adhesive from flowing through perforations in the liner material.
In U.S. Pat. No. 6,235,365, Schaughency et al. explained that split release sheets were useful for installing membranes in detail areas such as roof valleys. Split release sheets were also considered useful for when the membrane is applied as a flashing material around windows and doors because a portion of the membrane could be affixed into position, while the remaining portion of the membrane could be covered by the release sheet, and thus not stick to itself or prematurely adhere to the installation surfaces. It was further remarked that split release liner sheets could hinder application in some detail areas, because the applicator would have to deal with two portions of the release sheet liner if she wished to expose at once the entire face of the adhesive layer for attaching the waterproofing membrane. Pre-split release sheets required that the applicator remove both split portions at once during application on flat (non-detail) areas, rendering control and accurate placement difficult.
Schaughency et al. therefore disclosed cutting string located between the adhesive and release liner, for cutting the release sheet liner into smaller portions for selective removal of release liner portions from the waterproofing membrane. Cutting strings were also disclosed in World Patent Application WO2004/070108 by Hamdar et al. for selective removal of release liner.
The objective of the present invention relates to the flashing of the building surfaces, particularly complex or small detail areas, such as door openings, window openings, ductwork passages, and other building surfaces and openings. Methods of the invention involve the use of a flexible membrane flashing tape strip having a release sheet liner that is neither pre-split or perforated and that does not rely upon the use of cutting strings for selective removal of portions thereof. For example, the method can be used for large and flat installations, such as for roofing underlayment applications, as well as very small detail areas, such as around openings or across multi-level surfaces. In particular, methods of the invention are well-suited for installation on multi-planar surfaces, such as building surfaces which form corners and edges.